USN-3586-1: DHCP vulnerabilities

1 March 2018

isc-dhcp vulnerabilities

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 17.10
  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 LTS

Summary

Several security issues were fixed in DHCP.

Software Description

  • isc-dhcp - DHCP server and client

Details

Konstantin Orekhov discovered that the DHCP server incorrectly handled a large number of concurrent TCP sessions. A remote attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2016-2774)

It was discovered that the DHCP server incorrectly handled socket descriptors. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2017-3144)

Felix Wilhelm discovered that the DHCP client incorrectly handled certain malformed responses. A remote attacker could use this issue to cause the DHCP client to crash, resulting in a denial of service, or possibly execute arbitrary code. In the default installation, attackers would be isolated by the dhclient AppArmor profile. (CVE-2018-5732)

Felix Wilhelm discovered that the DHCP server incorrectly handled reference counting. A remote attacker could possibly use this issue to cause the DHCP server to crash, resulting in a denial of service. (CVE-2018-5733)

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 17.10
isc-dhcp-client - 4.3.5-3ubuntu2.2
isc-dhcp-relay - 4.3.5-3ubuntu2.2
isc-dhcp-server - 4.3.5-3ubuntu2.2
isc-dhcp-server-ldap - 4.3.5-3ubuntu2.2
Ubuntu 16.04 LTS
isc-dhcp-client - 4.3.3-5ubuntu12.9
isc-dhcp-relay - 4.3.3-5ubuntu12.9
isc-dhcp-server - 4.3.3-5ubuntu12.9
isc-dhcp-server-ldap - 4.3.3-5ubuntu12.9
Ubuntu 14.04 LTS
isc-dhcp-client - 4.2.4-7ubuntu12.12
isc-dhcp-relay - 4.2.4-7ubuntu12.12
isc-dhcp-server - 4.2.4-7ubuntu12.12
isc-dhcp-server-ldap - 4.2.4-7ubuntu12.12

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

In general, a standard system update will make all the necessary changes.

References